A. Field of the Invention
The invention relates to the field of container filling and, more particularly, to a method and means for removing temporary seals from containers as they pass into the filling line.
B. The Prior Art
In recent time, plastic containers have become increasingly utilized for the purpose of packaging milk or similar fluids. The plastic containers are usually blow molded from suitable plastic, such as polyethelene, at a manufacturing facility. The nature of the blow molding manufacturing process renders the interior of these containers sanitary. However, if, after the containers have been formed, they must be shipped, such as in a truck trailer, to a filling site or are otherwise exposed to foreign particles and vapors prior to filling, then additional steps need be taken so that the container interiors remain sanitary prior to being filled.
One method for insuring sanitary containers is to provide for a washing and sterilization of the inside of the containers just prior to being filled. This is extremely objectionable in that the installation of heavy and complex equipment would be required along the filling line.
A typical procedure for maintaining the initial sanitary condition of the blow molded plastic containers has been to package them at the manufacturing site in large polyethelene bags. The disadvantage of this procedure is that the packing is usually accomplished manually and unpacking similarly requires manual labor. Further, since the plastic containers are relatively lightweight, they often become crushed or irreparably dented during handling in the polyethelene bags.
There is disclosed in U.S. Pat. Nos. 2,995,883 and 3,067,552 a method for preventing glass containers from collecting foreign particles prior to being filled in which adhesive paper seals cover the mouth ends of the containers. U.S. Pat. No. 3,067,552 indicates that these seals are to be vapor-permeable to enable the evaporation of condensation occurring within the glass containers. U.S. Pat. No. 2,995,883 discloses nip roller means for removing the temporary seals from the container mouths. The sealed containers are spaced in seriatim on a conveyor and passed to the nip roller apparatus. Prior to reaching the seal removal rollers, a forwardly extending marginal portion of a seal is deflected upwardly by an air blast. While extending upwardly, the marginal portion of the seal is engaged by and maintained in its upwardly position by a guide wire leading to a nip between upper and lower rollers. The rollers rotate at high speed and in a forward direction to pull the seal off the container. The desealed containers pass under the lower roller and continue on their way to a filling machine or the like. This procedure would have unique disadvantages if utilized with plastic containers. Vapor-permeable seals would be ineffective for preventing entry of harmful vapors or water settling in blow molded sanitary containers. Since plastic containers are relatively lightweight, pulling a temporary seal from the container mouth would very likely lead to toppling of the container, which would threaten frequent jam-ups along the filling line conveyor. Further, since the lower roller comes into contact with the adhesive side of a temporary seal in this prior art procedure, there is the risk that seal surfaces will become glued to the lower roller or adjacent surfaces leading to a jam-up of the pinch roller operation.